from Hacker News

Smoke in the cabin of two 737 MAX caused by Load Reduction Device system [video]

by dz0ny on 2/9/25, 10:12 PM with 80 comments

  • by MobiusHorizons on 2/11/25, 12:27 AM

    I found this to be a fascinating dive into a potentially serious safety concern. I was impressed how simple the mitigations could be based on the recommendations in the report. I find the evidence credible for an attempt to burry the issue, but honestly I don't understand the motivation. At this stage I feel Boeing and the FAA could really stand to gain some good press from being extra proactive about such issues. Especially when the proposed mitigations seem like they would be relatively easy to implement, and should not be expensive for airlines from what I can see. It seems like the source being the engine manufacturer and consequently having the potential of affecting other jets including potentially the airbus A320 would only improve the incentives for Boeing to get out ahead of this, and demonstrate a safety culture. Does anyone understand the motivations that could lead to the response we have seen from the FAA and Boeing?

  • by dz0ny on 2/9/25, 10:29 PM

    This is a issue that may also affect Airbus aircraft, but so far, it has only caused problems on two Boeing planes. Like MCAS, it was not disclosed to pilots, prompting the FAA to recommend design changes and notify flight crews.

    https://simpleflying.com/boeing-cfm-international-update-737...

  • by DrNosferatu on 2/12/25, 12:52 PM

    Fascinating how many people had to actively shove this to the side so that it became potentially life threatening:

    - CFM designed an engine that, in certain emergencies, dumps oil into the quite possible (actually traditional, if I understand correctly?) human-breathing stream of the aircraft, apparently, without the relevant human-breathing system shutdown mandate when said (or any) emergency system is triggered; [truth be told, we never heard their complete story]

    - Boeing integrating said new engines into their new 737MAX without appropriately checking for possible new emergency mode interactions with their life-support (in this case, breathing) systems.

    - FAA dropped the ball upon accident investigation;

    - FAA removed their employee that then picked up the ball;

    - EASA swallowing what they were told by FAA without asking further questions;

    Well...

    I have worked in many no-harm potential software projects that employed more careful engineering than this.

    All hardware projects I worked on employed more careful engineering than this.

    Conclusion: It becomes more and more difficult to falsify that Boeing, nowadays, simply abandoned engineering design reviews, and, relies solely on some blend of "agile" methods to design people-carrying airplanes.

  • by toomuchtodo on 2/9/25, 10:46 PM

  • by dehrmann on 2/12/25, 7:06 AM

    tl;dw: when a particular engine design used by the 737 MAX (but also other Boeing and Airbus planes) ingests a bird, if there's enough damage, it starts burning oil before the cabin bleed air intake. The cockpit and cabin have air supplied from different engines. Since the cockpit is relatively small, if the cockpit engine was damaged, smoke would fill the cockpit quickly, reducing the pilots' visibility and requiring them to don air masks. Bird strikes only happen at takeoff and landing--times when pilots don't have time to be fiddling with masks and seeing through smoke and trying to shut off the damaged engine. Regulators in the US and EU don't seem especially concerned.

  • by hypothesis on 2/9/25, 11:26 PM

    I wonder what was the thought process there: hey we save an engine maybe, but everyone inside the plane gets cooked in 39 seconds. Ship it!

    Comments on that youtube video are filled with industry insiders and it’s just wild. They even think someone has died from a similar fuming event back in December…

  • by pxeger1 on 2/12/25, 7:59 AM

    This guy says he doesn’t understand why the issue isn’t taken more seriously, and that he’s tried to cover every possible hole in his logic. Here’s a possible reason:

    None of the sources he references about the danger of the smoke itself appear to be very confident that it genuinely could kill you in 39 seconds, and they all seem to be from sites that likely have an incentive to sensationalise. Maybe he had better sources for that claim, but didn’t show them (or maybe I didn’t watch the video carefully enough), but I wasn’t convinced that it’s actually true.

    But if not, It’s possible the FAA/Boeing have better data or other reasoning that makes them sure that the smoke is not that dangerous. In which case their inaction (but not necessarily their PR strategy...) seems more justifiable.

  • by DrNosferatu on 2/12/25, 1:47 PM

    One more reason not to fly Ryanair!

  • by xeonmc on 2/11/25, 6:58 PM

    Could this also have been activated in the Jeju air crash from the initial bird strike?